powerpc/32: Statically initialise first emergency context

powerpc/32: Statically initialise first emergency context

[ Upstream commit a4719f5bb6d7dc220bffdc1b9f5ce5eaa5543581 ]

The check of the emergency context initialisation in
vmap_stack_overflow is buggy for the SMP case, as it
compares r1 with 0 while in the SMP case r1 is offseted
by the CPU id.

Instead of fixing it, just perform static initialisation
of the first emergency context.

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/4a67ba422be75713286dca0c86ee0d3df2eb6dfa.1615552867.git.christophe.leroy@csgroup.eu
Signed-off-by: Sasha Levin <sashal@kernel.org>